Water Level Controller

WATER- LEVEL CONTROLLER

CHAPTER 1

BLOCK DIAGRAM

EEE Dept .College of Engineering Kidangoor

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1.1 BLOCK DIAGRAM

Fig.No.1


POWER SUPPLY

WATER LEVEL SENSING UNIT

PUMPCONTROL

UNITPUMP

DRYCONDITON

SENSING UNIT&

BUZZER

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1.2 BLOCK DIAGRAM DESCRIPTION

1.2.1 POWER SUPPLY Power supply is obtained using a 230/15v step down transformer. This is then rectified using bridge

rectifier and filtered using capacitor filter .Then it is given to a regulator IC (7812).The output of the

regulator IC is used for the working of the circuit.

1.2.2 WATER LEVEL SENSING UNIT

The tank is used to fill the water. Certain provisions are provided in the tank, so that we can

automatically control the water level. The tank is provided with three electrodes (L, B, and U).

These electrodes are suspended into the tank .

1.2.3 PUMP CONTROL UNIT

This unit senses the water level by the indication of electrodes and controls the pump. If the level L

is achieved, the tank is automatically filled by the pump. If level U is achieved, the pump stops filling

automatically. Manual switch on/off of pump is also possible.

1.2.4 PUMP

This is the final part of the block diagram .Using the provision for control; we can control the

working of the pump. The motor used here is 230v induction motor.

1.2.5 DRY CONDITION SENSING UNIT

When the motor runs dry, this unit senses and activates the buzzer circuit. For sensing, two

electrodes (A,B) are used. When A and B, and motor runs then it activates the buzzer circuit and

alarms sound to switch off the motor manually. This unit will be only active when the motor is

working.


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CHAPTER 2

CIRCUIT DETAILS


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2.1 CIRCUIT DIAGRAM

Fig.No.2


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2.2 PLACING OF ELECRODES INSIDE THE TANK

Fig.No.3

2.3 PLACING OF ELECTRODES ON PIPE

Fig.No.4


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2.4 CIRCUIT DETAILS

Power supply is obtained through step-down transformer X1, diode D1 through D4,

capacitor C1, series current limiting resistor R1, regulator IC (7812) and noise-filtering capacitors C2

and C3. The input of the regulator IC can be varied from 15 to 35 v. Using a 230 / 15 v transformer, ac

mains is stepped down and rectified. After filtering, it is given to regulator IC the output of the IC is

regulated 12 v dc, which is fed for the working of the circuit.

The water level controller circuit is built around IC 555to monitor the water level

in the tank. The pin 6 sense the lower level and pin 2 senses the upper level. The output of IC 555

controls the on/off status of the motor through the inverter and driver circuit. The LED indicates the

status of the motor. There are two switches S2 and S3, whitch are used for control the motor manually.

As the value of resisters R2 and R3 are very high, corrosion of electrodes is very little. Freewheeling

diode D5 prevents chattering of the relay coil due to the back emf produced by the relay coil.

The alarm circuit is enabled only when the motor pump runs. Diode D6 isolates

the relay driver circuitry to prevent transistor T3 from extending ground to the relay through transistor

T3 .As soon as the pump is switched on, the alarm sounds until water reaches the delivery port.

For the sensor electrodes, use a molded –type AC chords (used for tape

recorders) or metallic bars. These electrodes are suspended into the tank from a longitudinally cut PVC

pipe. The arrangement for the dry pump sensor is shown in figure 2.3 .The electrodes can be attached

firmly to the delivery pipe such that water falls onto the plug leads. Regarding the lab note of

maintaining gap of the sensor (L, B and U),it is advised for the sake of proper sensitivity. But this is

need to be strictly adhered to, through it advisable to keep electrodes as near as possible. There is no

ready made PCB available for this circuit. Since the circuit has two ICs, a breadboard is enough.


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CHAPTER 3

WORKING OF THE PROJECT


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3.1 WATER LEVEL BELOW THE LOWEST LEVEL

When water in the tank is below the lowest level L1, all the electrodes are electrically

separated and hence points L and U (pins 6 and 2 of IC2,respectively) are pulled up to the sup-ply

voltage through resistors R2 and R3, respectively. Therefore, to reset IC2 the output of IC2 at pin 3 goes

low. As a result, transistor T1 stops conducting to drive transistor T2 and relay RL1 energises. The

motor pump now starts running to fill the tank with water. Freewheeling diode D5 prevents chattering of

the relay due to the back emf produced by the relay coil.

3.2 WATER LEVEL RISES TO BRIDGE ELECTRODE

When the water level rises to bridge the electrodes, because of the conductivity of

water, pin 6 (E1) is pulled down to ground (E2). This does not alter the output state of IC2, which

maintains its previous state, and the motor keeps running.

3.3 WATER LEVEL RISES TO OVRFLOW LEVEL

When water rises to the overflow level L2 and touches electrode E3, point U (pin 2 of

IC2) is connected to already sunken ground electrode E2, thereby triggering it. IC2 resets to give a high

output at pin 3. This is inverted by transistor T1 to cut off transistor T2 and de-energises relay RL1. The

motor pump now stops to prevent water overflow.

3.4 AS WATER LEVEL FALLS DOWN

As water is consumed, the water level comes down leaving electrode E3 isolated from

ground electrode E2. Now point U (pin 2 of IC2) is pulled up to the supply voltage. This does not

change the output state of IC2 and the motor remains switched off. When water level again falls be low

electrode E2, IC2 resets to cut off transistor T1. Transistor T2 conducts to energize relay RL1 and the

motor is powered to run. This is how the process continues. LED1 glows whenever the relay energises,

indicating that the motor pump is running.


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3.5 WHEN PUMP RUNS DRY

When the pump runs dry, points A and B are electrically apart causing transistor T3 to cut

off because of pull-up resistor R6. Transistor T4 conducts due to the emitter drop of transistorT3, which

activates the DC buzzer to sound an alarm indicating dry running of the pump. The alarm circuit is

enabled only when transistor T2 conducts, i.e., only when the motor pump runs.

3.6 TESTING OF THE CIRCUIT

To test the circuit, proceed as follows:

1. Switch on power to the circuit.

2. LED1 glows and relay RL1 energises to produce an alarm from piezobuzzer PZ1, indicating that none

of the circuit points A, B, U and L is shorted through water (i.e., water in the tank is below the lowest

limit). The energised relay indicates ‘on’ status of the motor.

3. Immerse points A and B in water. The buzzer stops sounding to indicate that water is flowing out

of the pipe to short points A and B. This confirms no dry run.

4. Immerse points B and L in water, as would be the case when the water level rises. Momentarily touch

point U to water. LED1 goes off and the relay de-energises to turn the pump ‘off.’ This would be the

case when water touches the overflow limit.

5. Remove points A and B from water assuming that the flowing water that was shorting points A and B

has stopped. Now, although water is not flowing, the buzzer does not sound as the relay is already de-

energised.

6. Remove points U and B from water, assuming that water has fallen below the lowest limit because of

consumption. Two seconds later, LED1 glows and the relay energises.

3.7 PRECAUTIONS

1. Make sure that water being delivered from the water pipe doesn’t touch any of the suspended water-

level sensors.

2. Mount the alarm sensor firmly onto the water pipe such that electrodes A and B are shorted by water

flowing out of the pipe.

3. Use a properly shielded cable to carry signals from the tank to the water-level controller unit.


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CHAPTER 4

PRINTED CIRCUIT BOARD (PCB)


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4.1 PCB LAYOUT

Fig. No. 5


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4.2 PCB FABRICATION

4.2.1 What is PCB?

PCB is a platform where the electronic components can be interconnected without wiring.

Now a day the printed circuit board here after mentioned as PCBs makes the electronic manufacturing

as easy one. In olden days vast area was required to implement a small circuit to connect the leads of

the components and separate connectors were needed. But PCBs connects the two by copper coated

lines on the PCB boards. In the single sided PCBs the copper layer is on both sides. Some cases,

middle layer is also possible than the two sides.

4.2.2 BOARD TYPE

The most popular board types are:

SINGLE SIDED BOARDS: They are mainly used in entertainment electronics where manufacturing

costs have to be kept at the minimum.

DOUBLE –SIDEDBOARDS: Double sided PCBs can be made with or without plated through holes.

The production of boards with plated through holes is fairly expensive.

Manufacturing process

First, we draw the wanted circuit on paper and it is modified or designed. PCB layout is to be drawn on

the plain copper coated board. These boards are available in two types

Phenolic

Glass epoxy

Most computers PCBs are glass epoxy. To draw circuit diagram we can use the black color paints.

Before that the required size of the plane PCB board is determined from the roughly drawn PCB layout.

Using black paint the desired circuit is drawn on the board.

Layout approaches

The first step is to prepare each and every PCB layout as viewed from the component side. Another

important attitude is not to start the designing of a layout unless an absolutely


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clear circuit diagram is available, if necessary, with a component list. Among the components the larger

ones are placed first and the space between is filled with smaller ones. Components requiring

input/output connections come near the connectors. All components are placed in such a manner that

desoldering of other components is not necessary if they have to be replaced.

In the designing of the PCB layout it is very important to divide the circuit in the functional sub unit.

Each of these sub units should be realized on a defined portion of the board. In the designing the inter

connections which are usually done by pencil lines, actual space requirements in the art work must be

considered. In addition the layout can be rather roughly sketched and will still be clear enough for art

work designer.

4.2.3 BOARD CLEANING

The cleaning of the copper surface prior to resist applications is an essential step for any

types of PCB process using etch or plating resist. Insufficient cleaning is one of the reasons most

encountered for difficulties in PCB fabrication although it might not always be immediately recognized

as this .But it is quite often the reasons of poor resist adhesion, uneven photo resist films, poor plating

adhesion etc.

Where cleaning has to be done with simplest means or only for a limited quantity of PCBs,

manual cleaning process is usually used. In the process we require just a sink with running water,

pumice powder, scrubbing brushes and suitable tanks.

4.2.4 SCREEN PRINTING

This process is particularly suitable for large production schemes. However the preparation of

a screen can also be economically attractive for series of 1000 PCBs. Below, while photo printing is

basically the non accurate method to transfer the pattern on to a board surface. With the screen printing

process, one can produce PCBs with a conduction width of as low as 0.5 or + or – and a registration

error of 0.1 mm on an industrial scale with high reliability.

In its basic form, a screen fabric with uniform meshes and opening is stretched and fixed on a solid form

of metal or wood. The circuit pattern is photographically transferred on to the screen, leaving the meshes

in the pattern open, while the meshes in the rest of the area are closed. In the actual printing step, ink

forced by the moving squeegee through the open meshes onto the surface of the material to be printed.


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4.2.5 PLATING

From a practical stand port, PCBs must have to be stocked before being taken for assembly of

components. It is expected that the circuit board retain its solder ability for long periods of several

months so that reliable solder joints can be produced during assembly. Plating of a metal can be

accomplished on a copper pattern by three methods:

• Immersion Plating

• Electro less plating

• Electroplating

4.2.6 ETCHING

This can be done by manual and mechanical ways by immersing the board into a solution of

formic chloride and hydrochloric acid and finally cleaning the board by soap. In all subtractive PCB

processes, etching is one of the most important step. The copper pattern is formed by selective removal

of all unwanted copper, which is not protected by an etch resist. This looks very simple at first glance,

but in practice there are factors like under etching and overhang which complicate the matter especially

in the production of fine and highly precise PCBs. Etching of PCBs, as required in modern electronic

equipment production, is usually done in spray type etching machines.

Component placing

The actual location of components in the layout is responsible for the problems to be placed

during routing interconnections. In a highly sensitive circuit, the critical components are placed first and

in such a manner as to require minimum length for the critical conductors. In less electrical circuit, the

components are arranged exactly in the order of signal flow. This will result in a minimum overall

conductor length. In a circuit where a few components have considerably more connecting points than

the others. These key components are placed first and the remaining ones are grouped around them.

The general result to be aimed at is always to get shortest possible interconnections. The bending

of the axial component leads is done in a manner to guarantee an optimum retention of the component of

PCB. The lead bending radius should be approximately two times the lead diameter. Horizontally

mounted resistors must touch the board surface to avoid lifting of solder joints along with the copper

pattern under pressure on the resistor body. Vertically mounted resistors should not be flush to the board

surface to avoid strain on the solder joints as well as on the component lead junction due to different

thermal expansion coefficients of lead and board materials, where necessary resilient spaces have to be

provided. Especially when plated through holes where the solder flows up in the hole, clean leads of at


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least 1 mm above the board are recommended. We carefully place the components according to the

instructions above.

4.2.7 DRILLING

Drilling of component mounting holes into PCBs is far the most important mechanical

machining operation in PCB production processes. Holes are made by drilling wherever a superior hole

finish for plated-through hole processes is required and where the tooling costs for a punching tool

cannot be justified. Therefore drilling is applied by all the professional grade PCB manufacturers and

generally in smaller PCB production laboratories. The importance of hole drilling into PCB has further

gone up with electronic component miniaturization and it needs smaller hole diameters and higher

package density where hole punching is practically ruled out.

4.2.8 SOLDERING

Soldering is a process for the joining of metal parts with the aid of a molten metal(solder), where

the melting temperature is suited below that of the material joined, and whereby the surface of the parts

are wetted, without then becoming molten.

Soldering generally implies that the joining process occurs at temperature below 450 degree

centigrade. Solder wets and alloys with the base metals and gets drawn, by capillary action, into the gap

between them. This process forms a metallurgical bond between the parts of the joint. Therefore solder

acts by

• Wetting of base metal surfaces forming joint.

• Flowing between these surfaces, which result in a completely filled space between them.

• Metallurgical bonding to these surfaces when soldered.

The basic constituents in making a soldered joint are represented in the diagram.

Base metal

Solder Heat Flux

Soldering consists of the relative positioning of the surfaces to be joined, wetting these surfaces

with molten solder and allowing the solder to cool down until it has solidified. During these soldering

operations, an auxiliary medium is mostly used to increase the flow properties of molten solder or to


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improve the degree of wetting. Such a medium is called flux. Following characteristics are required in a

flux:

• It should provide a liquid cover over the materials and exclusive air up to the soldering

temperature.

• It should dissolve any oxide on the metal surface or on the solder and carry such unwanted

elements away.

• It should be readily displaced from the metal by the molten soldering operation.

• Residues should be removable after completion of the solder.

To achieve a soldered joint the solder and the base metal must be heated above the melting point of the

solder used. The method by which the necessary heat is applied, among other things depend on:

• Nature and type of the joint

• Melting point of the solder

• Flux

Generally applied soldering methods are iron soldering, torch soldering, mass soldering, electrical

soldering, furnace soldering and other methods. Components are basically mounted on

only one side of the board. In double-sided PCBs, the component side is usually opposite to the

major conductor pattern side, unless otherwise dictated by special design requirements.

The performance and reliability of solder joints give best results if lead cutting is carried out before

soldering so that the lead ends get protected and also covered with solder and herewith contributing, to

the actual solder connections. However, lead cutting after soldering is still common, in particular, in

small industries where hand soldering is used.

With the soldered PCB, many contaminants can be found which may produce difficulties with the

functioning of the circuit. The problems usually arise at a much later than during the final functioning

testing of the board in the factory. Among the contaminants, we can typically find flux, chips of plastics,

metals and other constructional materials, plating sails, oils, greases, environmental soil and other

processing materials.

The following performances are expected from the cleaning procedure with the appropriate cleaning

medium.

• Dissolution or dissolving of organic liquids and solids, e.g., oils, greases, resin flux.

• Removal of plating salts and silicon oils.

• Displacing of particulate and other insoluble matters, e.g., chips, dust, lint.


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• No severe attacks on boards and components to be cleaned, no alteration of link or paint

notations and last but not the least, compatibility with healthy environmental conditions.

CAD in PCB

First the PCB layout is designed by ORCAD in our CAD lab. Then we took the printout of the layout

obtain from the computer (of larger size) for out clearance. This layer is given to the photography

section to get the layout. The exposed mesh is placed on plane copper coated board in correct alignment

by using wooden clamps paint flow through the board and the layout lines are made on the copper

boards.


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CHAPTER 5

COMPONENTS DETAILS


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5.1 COMPONENTS

COMPONENT NAME NUMBER COSTIC 1 7812 1 10 RsIC 2 NE 555 1 7 Rs

D1 – D2 1N 4007 6 3 RsLED1 LED 1 2 Rs

T1 & T4 BC 548 2 3 RsT2 SL 100 1 10 RsT3 BC 558 1 3 RsR1 10 ohm 1 0.5 Rs

R2,R3 & R4 1M ohm 3 1.5 RsR4, R5 & R7 10K ohm 3 1.5 Rs

R8 1K ohm 1 0.5 RsC1 (+ -) 1000 uF 1 3 RsC2 & C3 0.1 uF 2 2 Rs

C4, C6 & C7 1uF 3 3 RsC5 0.01uF 1 0.5 Rs

RL 1 12 V,200 ohm,SPST 1 10 RsX 1 230 /15 V ,300 mA 1 55 Rs

PUSH TO ON SWITCH

1 5 Rs

PUSH TO OFF SWITCH

1 5 Rs

BUZZER 1 15 RsBREAD BOARD 1 85 Rs

TOTAL= 255 Rs


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CHAPTER 6

CONCLUSION


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6.1 APPLICATIONS

1. The circuit can be implemented in house for effective usage of water and electricity

2. It can be used in Municipal Corporation to pump water

3. It can be implemented in larger industries (Dying Industries)

6.2 FEATURES

1. Simple and economical

2. Manual on/off of motor is possible

3. Indicates the status of motor

6.3 FUTURE EXPANSIONS

1. It can used in any industry concerned with fluids.

2. By replacing the electrode with light sensitive or IR sensors this can be used in other fluids

6.4 CONCLUSION

The circuit of Water Level Controller id designed and the successful working verified.

The project has been successfully completed and it provides an opportunity to understand us about the

PCB fabrication design of the circuit and selection of miscellanies components. It also gives ability to do

various other complex designs.


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CHAPTER 7

REFERENCE


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7.1 REFERENCE

1. ELECTRONICCS FOR YOU –CIRCUIT IDEAS ,DECEMBER 2005,pp 95 – 96

2. http://www.efymag.com/

3. http://www.efu.com/

4. http://www.futurlec.com/

5. http://datasheets.com/

By Nithin Raj


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S6 EEECollege of Engineering Kidangoor


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Documents

Water Level Controller